Blast diffusing means for electric circuit breakers of the fluid-blast type



fan. 26, 195% J. w. BEATTY ET AL Z,6@79555 BLAST DIFFUSING MEANS FORELECTRIC CIRCUIT BREAKERS OF THE FLUID-BLAST TYPE Filed May 21, 1952 2Sheets-Sheet l Fl k. a g

g 6 l A 7 ,9 2 l 2 L" al 6/ I 6 44 I 47 a 24 5 I 1; 45 as g I, 46z/vsamr/a/z/ 0 J 56 27 55? as lvfivehtov s:

John W Beatt Haw-old N. Schneidev;

J. W. B TTY ET AL FFUSING ME FOR ELECTRIC CIRCUIT AKERS OF THEFLUID-BLAST TYPE Jan. 26, 1954 BLAST DI BRE -2 Sheets-Sheet 2 Filed May21, 1952 w H stw om w t e P O o B o. n .s m ew v .m d e mm o /w r a H Hb Patented Jan. 26, 1954 e I I UNITED STATES BLAST DIFFUSING MEANS FORELECTRIC CIRCUIT BREAKERS OF THE FLUID-BLAST Schneider, Springfield,Pa., assignors to General Electric Company,

York

Application May-2r; 1952, Serial No; 289,082

This invention relates to blast diffusing means for electric circuitbreakers of the fluid blast type and more particularly to an arrangementwherein a blast diifuser is interposed in a fluid passageinterconnecting the circuit breaker contacts and la v ve used to. entrth vflew .qtfltuid mm a r e such we re e vqir- T ,hi a e.s c r r u ib eaers. of the gas blast type, especially where a long-stroke isolatingblade coactswith a short-strokeinterrupting contact, it is frequentlynecessary because of the high voltage rating of the circuit breaker, tosupply a blast ofgas thrqugh a long passage or arcing chamber'leadingfrom the blast valve to the arcing zoneof the circuit breaker. Due tothe fact that the connecting passage between the blast valve and thecircuit breaker contacts is quite long and because pressure of the gascontained in the reservoir is rather high, of the order of'250 poundsper square inch, it has been observed that blast pressure oscillationsand aberrations of substantial amplitude travel along the passage to theregion of the arcing contacts and that such Wide variations producecorresponding fluctuations in insulating strength which can interferewith the proper functioning of the circuit interrupter by causingunpredictable voltage breakdowns or restrikes during the interruptingprocess, especially when performing capacitance switching.

A principal object of this invention is to provide means forsubstantially reducing pressure oscillations in the region of the arcingzone of the contacts of a fluid blast circuit breaker so as to precludefortuitous failures of interruption of the breaker; v a

In accordance with the invention, blast diffusing means is interposedbetween the blast valve and the contacts of a fluid blast circuitbreaker which means effectivelyreduces harmful irregular aberrations in'the pressure of the fluid in the region of the contacts. Such pressurediffusing; means generally may take the form of any honeycomb devicesuch as a plurality of corrugated metallic layers interspersed withother layers of sheet metal so as to form a plurality of parallelpassages through which the blast passes en route to the contacts of thecircuit breaker to thereby produce a mixing through turbulence foreffectively damping harmful oscillations in the fluid pressure such asare producedby the pressure wave front and'its ensuing reverberations.

For a better understanding of theinvention, reference may be had to thefollowing description taken in conjunction with the drawing in whichFig. 1 represents schematically a circuit breaker of the gas blast typeembodying the principles of the invention, in which Fig. 2 is anenlargedlcross-sectional. view alongathe line 2-4 of .1. andin.which;Eig...3. is'lan. enlargedlver-s a corporation of New' 2' v ticalsection of a portion of the structure shownin Fig. -1.

In the drawing the numeral 1 generally designates an interrupting unitcomprising one pole of a gas blast circuit breaker. Th supply ofpressure fluid to interrupting unit I is supplied; through blast valve},whichis under the control of opening control valve 3, from a source-pf;fiuid pressure 4. Once the circuit controlled; by the breaker hasbeeninterrupted by interrupter. unit I, a circuit isolatin operation of thebreaker;

is accomplished due to operation of fluid-ach ated device 5 as will bemore fullyexplained I Interrupterunit l comprises metallic enclos ingstructure 6 which supports finger contacts l biased by spring means 8into engagementwith tubular contact 9. Theenclosingstruc ture Bsupported by an insulating casing III which in turn is mounted uporrthemetallic base member II. The specific construction of the unit I is morefully described and is claimed in applica-.

tion Serial No..233,637-Beatty, filed June 26, 1951, and an interruptero f th general type dis; closed in Fig. 1 is disclosed andbroadly'claiined in application Serial No. 202,100 -Beatty, filedDecember 21, 1950, now Patent No. 2, 45,697,; issued July 14, 1953, bothof which applications are assigned to the assignee of this invention.

The interrupting finger contacts 1 are separated tween these contacts.This supply of gas flows in the direction of the arrows to atmosphereand is supplied to the blast valve 2 from the air receiver 4 through theshort conduit 12. The terminals of the breaker are indicatedschematically by a line connected to member 6 and by another line whosearrow represents a sliding contact with. the movable isolating tubularcontact 9.

Blast valve 2 the balanced-typeand com -1 prises a pair of disksl3mounted on-a' valve" spindle 15 on which is disposed a main operatingpiston 16 and a valve restraining piston; Li. The valve is biasedtowardthe closed positionby spring means [4. A conduit I8 interconnectsopeningcontrol valve 3 with the enclosing struc ture [9 in which themain operating piston 16 is movable. As illustrated, opening controlvalve 3 is of the electromagnetically actuated type Opening controlvalve 3, as is well known, could be. responsive to an electric conditionof the systern controlled. byv the breaker electric condition ofthesystem controlled by the-breaker I :Valve 3 -also. could .be.manually actuated or,-of cou-rse, Y

could be both manually and automatically operable.

Full opening movement of blast valve 2 is accomplished when openingcontrol valve 3 is opened. Opening of the opening control valve 3supplies pressure fluid underneath the piston l6 and causes the valve 2to move to its fully opened position. In this way a major blast issupplied to the interrupting unit I to separate the finger contacts Ifrom the tubular contact 9 and to extinguish an are drawn between thesecontacts. When blast valve 2 is reclosed due to the closing of conrolvalve 3 and to the action of spring M, the blast pressure in interruptercasing ID will decay so that the contacts I will return to the positionillustrated due to the bias of their individual closing springs 8.

After interruption of an are drawn between the contacts I and 9, asuitable isolating gap is established before the blast of fluid is shutoff. To this end the arrangement shown in the drawing is constructed sothat the tubular contact 9 can be drawn downwardly, during, after orcoincident with the interrupting or blasting operation. Isolatingcontact 9 is connected at its lower end to a vertical operating rod 29of insulating material which is pinned at 2| to a switch lever 22 whichin turn is pivoted at 23 to a guide link 24 mounted at fixed pivot 25.Operating crank 26 mounted for rotation about a fixed pivot 21 is pinnedat 28 to the lever 22. Opening bias for contact 9 is supplied in theform of compressional spring 29 which biases a transversely disposed rod30 toward the right. Rod 39 is pinned to bell crank 26 at 3|. Spring 29normally is inefiective to separate isolating contact 9 frominterrupting finger contacts 1 due to the toggle construction comprisinglinks 32 and 33 which are pinned together at 34. Rod 30 is connected tolink 33 through bell crank 35 pivotally mounted at the fixed pivot 36and pinned at its upper extremity to rod 39 by pin 31 and at its lowerend to link 33 by a pin 38. Link 32, which really is one member of athree-armed crank, is mounted on a fixed pivot 32a. With the togglecomprising links 32 and 33 in the overcenter position indicated, thebias of spring 29 is ineffective to separate the contacts. However, ifthe toggle is moved downwardly through dead center and beyond, thespring 29 then imparts a rapid opening movement to the contact 9 throughits operating rod 29 and parts associated therewith. The lower positionof rod 29 and of switch lever 22 are indicated by dotted lines and thefull isolating stroke is indicated by the distance S. Opening movementof the parts is arrested when roller 3811 on bell crank 26 engagesbufier or dashpot 38b.

For the purpose of breaking the toggle comprising links 32 and 33, thefluid-actuated device is arranged to respond to the opening of controlvalve 3 and the resulting operation of the blast valve fluid motorcomprising piston IS in the cylinder structure l9, thus ensuring thatthe interrupting contacts are blown open and blasted prior to breakingthe toggle whereby to initiate the isolating movement of contact 9.

Fluid-actuated device 5 is provided with an enclosing cylinder 39 and anopearting piston 40. Thus, when fluid pressure is supplied above piston40, downward motion will be imparted thereto so as to break the toggle32-33 whereupon spring 29 quickly opens the isolating contact 9.

Fluid pressure is supplied above the piston 49 by means of a conduit 4|which connects to the 4. enclosing structure l9. Blast valve spindle I5is provided with an undercut portion 42 and fluid pressure is suppliedfrom opening control valve 3 to the structure l9 through forked conduitsl8 and 43. Thus, when opening control valve 3 is opened, fluid pressurein conduit l8 will cause the blast valve piston Hi to move upwardly.Responsive to such valve opening movement, fluid pressure suppliedthrough conduit 43 passes through the structure I9 to the conduit 4| tooperate piston 49 of fluid-actuated device 5 as a result of the undercutportion 42 of the spindle I5 establishing communication between conduits43 and 4|. Thus, it is impossible to supply fluid to the device 5 tocause isolating movement of contact 9 unless the blast valve 2 has beenopened. This particular interlocking arrangement is more fully disclosedand claimed in application Serial No. 233,542-Shores, filed June 26,1951.

As already mentioned, a full breaker opening stroke is completed withthe opening of the isolating contact 9; the cycle being terminated bythe timed reclosing of the closing valve 3 as through the operation ofan auxiliary switch actuated by some appropriate moving part during thedownward stroke of the piston 49 of the pneumatic operator 5. Thus,pressure below the blast valve piston I6 is relieved through theatmospheric vent of the closing control valve 3 so that the blast valve2 closes under the urge ofits spring l4, while pressure above the motorpiston 49 is relieved, when the blast valve'closes, through the vent toatmosphere in the structure I!) adjacent the undercut portion 42 of theblast valve spindle, the opening spring 29 ensuring that a full openingstroke is attained by the isolating contact 9.

Since the finger contacts 1 return to the position indicated due to theaction of biasing means 8 after the fluid blast is cut oil, closure ofthe breaker is accomplished by imparting upward movement to the contact9. To this end, fluid pressure is supplied to the underside of piston 40of device 5 to cause upward movement thereof and movement of theoperating linkage against the bias of spring 29 to close the breaker.Fluid pressure is supplied to the lower portion of structure 39 by meansof breaker closing control valve 44 which, as indicated schematically onthe drawing, is of the electromagnetically operated type. Valve 44 isconnected with cylinder 39 through a conduit 45a and is constructed soas to vent the lower portion of cylinder 39 to atmosphere when closed.Fluid pressure is supplied to valve 44 through suitable means such asthe conduit 44a.

In order to prevent an arc from striking between contacts I and 9 ascontact 9 approaches the closed position, it is desirable to supply aminor blast of gas to the contacts. blast is supplied by opening thevalve 2 a partial distance only. In this way, the sup-ply'of pres-,

sure fluid in air receiver 4 is not needlessly wasted. For the purposeof imparting partial opening movement to blast valve 2, a fluid motorcomprising piston 45 and a restraining means in the form of piston H areprovided, such structure being disclosed and claimed in applicationSerial No. 244,064 by Harold N schneider and Reed M. Anderson which wasfiled on August 28, 1951, and which is assigned to the assignee of thisinven tion. Fluid pressure is supplied to pistons l1 and 45 throughconduits 46 and .41 from an auxiliary valve comprising undercut portion48 of a slidable member 49 which is movable in accord- This minor ancewith movement of piston 40. Fluid pressure is supplied to conduit ltfrom the lower portion of cylinder 30 through port 55 due to theestablishment of communication between port 50 and conduit :35 as theundercut portion it of control member ii moves Fluid pressure s liedthrough conduit bears against surface of restraining piston ii andthrough conduit Lil is caused to bear against the lower surface ofpiston d which is of larger diameter than piston it. It will be observedthat the travel E of piston s5 is less than the travel A of piston it.Thus, fluid pressure supplied below piston 5-5 will impart upwardmovement to valve stem 55 to force valve 2 to open partially. Valve 2,being provided with the two disks i3, is of the balanced type. Thus, themomentum of the parts, being sumcient to overcome the force of springit, would cause the valve to open fully once it is partically opened bypiston 45. To prevent such as occurrence, the piston H is arranged toexert a downward force on the valve spindle 55 so as to maintain thevalve 2 in a partially opened position for producing a minor closingblast as determined by the position of piston 555 after that pistoncompletes its upward. travel distance 3. l -urthermore, piston ll causesa slower opening of the valve than when the valve is opened by piston 65during opening of the breaker.

In accordance with this invention, a blast diffuser structure 5i ismounted within the casing in between the blast valve 2 and the zone ofarcing. Diffuser 5i includes a retainer structure 52 with a bell mouthportion 53 at the lower end thereof which is provided with six radiatingweb members 54. Similarly, six spider elements 55 radiate from the upperend of the retainer 52. Disposed about the retainer 52 and its web 54and spider elements 55 is a sleeve member 55 which is secured to thebase member l I by a threaded engagement. Between the radially extendingwebs 54 and the radially extending spider members 55 is wound a scrollstructure comprising a fiat metal sheet 5? and a corrugated metallicelement 55 to form a suitable foraminous structure.

The sleeve 55 is brazed to the spider elements 55 and to the webelements 54 so as to form a unitary removable unit 5!.

For the purpose of guiding the vertical reciprocatory motion of theisolating contact 9, an insulating ring 59 is secured within anappropriate groove formed within the inner periphery of the retainer 52.Preferably, the ring 59 is constructed of a hard, smooth, low frictionmaterial.

From Fig. 3 it will be observed that the diffuser unit 5! is screwedinto a strong metallic member of the structure, shown in this instanceas the blast valve housing flange, so that the sleeve 56 constitutes areinforcing wall for taking at least a portion of the inwardly exertedpressure due to the split halves of the wedged clamping ring 60 whichare secured in position by bolts GI and lugs 62, thereby to preventdistortion of the easing II).

For best results, the diffuser element 5| is disposed in a region whichis between the blast valve and the interrupting contacts so as toprovide a direct flow path from the downstream side of the diffuser tothe interrupting contacts, 1. e., at a place where direct flow from thediffuser to the contacts is then possible without any material change inthe direction of flow. Furthermore,

the diffuser should be disposed as close to the interrupting contacts asthe voltage conditions permit.

Preferably then, the difiuser element 51 would be located toward themid-section of the casing it? rather than, as indicated by the somewhatschematic Fig. 1, being secured directly to the blast valve casing i I.

In other words, when applying the diffuser of our invention to its bestadvantage to an actual so KV. high voltage interrupter which wassuccessfully tested and is now operating in service, it was fasteneddirectly to the metallic supporting structure which houses the fixedisolating contacts, via, at the upper flange of the structure 6 of theaforesaid application of Beatty Serial No. 202,100.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electric circuit breaker of the fluid blast type comprising aninsulating cylindrical casing, a pair of contacts disposed within saidcasing, said contacts being separable to draw an arc to be extinguishedand one of said contacts being reciprocable within said casing, meansincluding a blast valve for directing a blast of fluid to said contactsfor extinguishing the are drawn therebetween upon separation thereof,and diffuser means disposed in the path of said blast for moderating theblast effect in a manner to eliminate harmful oscillations in thepressure of said fluid in the region of said contacts, said diffusermeans comprising an annular cylindrical retainer having an inner and anouter wall, a foraminous mass disposed between said walls, and a narrowanti-friction ring captured in said inner wall for guiding saidreciprocable contact.

2. An electric circuit breaker of the fluid blast type comprising asupport, an insulating cylindrical casing, a securing means for clampingsaid casing to said support, a pair of contacts disposed within saidcasing, said contacts being separable to draw an arc to be extinguishedand one of said contacts being reciprocable within said casing, meansincluding a blast valve for directing a blast of fluid to said contactsfor extinguishing the are drawn therebetween upon separation thereof,and diffuser means disposed in the path of said blast for moderating theblast efiect in a manner to eliminate harmful oscillations in thepressure of said fluid in the region of said contacts, said diffusermeans comprising an annular cylindrical retainer having an inner and anouter cylindrical wall, a foraminous mass disposed between said walls, anarrow antifriction ring captured in said inner wall for guiding saidreciprocable contact, and contractible means forming a portion of saidsecuring means for compressibly sealing one end of said cylindricalcasing to said outer cylindrical wall, said outer wall serving toreinforce said casing against the compressive action of saidcontractible means- JOHN w. BEATTY.

HAROLD N. SCHNEIDER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,298,838 Paxton Oct. 13, 1942 2,382,850 Bennett Aug. 14, 19452,552,358 Whitney et a1 M May 8, 1951 FOREIGN PATENTS Number CountryDate 532,670 Germany Sept. 2, 1931

